Drying alters the phenolic constituents, antioxidant properties, α‐amylase, and α‐glucosidase inhibitory properties of Moringa (Moringa oleifera) leaf

Abstract

Moringa oleifera leaf is a popular green leafy vegetable which has found its usefulness in the preparation of traditional stews and soups. Like most green leafy vegetable which are not around year‐round, the leaf is usually dried and pulverized for storage and easier handling, and despite the popularity of this processing technique, there is dearth of information on how drying affects the health‐promoting properties of the leaves. Hence, this study sought to investigate the effect of some drying methods (freeze‐drying, sun, air and oven drying) on the phytoconstituents, antioxidant properties, and biological activities of moringa leaf. This study revealed that drying methods significantly altered the phytoconstituents (phenolics, flavonoids, vitamin C, tannin, saponin, phytate, oxalate, alkaloid, cardenolides, and cardiac glycosides), antioxidant capacities (reducing power, Fe2+chelating, ABTS •+, DPPH, and • OH scavenging abilities), and enzyme inhibitory (α‐amylase and α‐glucosidase) effects of the leaf, with freeze‐drying being the most promising method for preserving the nutraceutical properties of moringa leaf. However, for practical application, the order of preference of the drying methods which ensures adequate retention of phytoconstituents and possibly biological activities of the leaf as observed in this study is freeze‐drying > air drying > sun drying > oven drying, in the order of decreasing magnitude.

Comprehensive Investigation of Moringa oleifera from Different Regions by Simultaneous Determination of 11 Polyphenols Using UPLC-ESI-MS/MS

“…As shown in Tables 4 and 5, the contents of isoquercetin, rutin and chlorogenic acid were much higher than those of other polyphenols. These results are consistent with the results described in previous studies [34,38,39]. At the same time, kaempferide and baicalin levels were below the detection limit.…”

First Report on Evaluation of Basic Nutritional and Antioxidant Properties of Moringa Oleifera Lam. from Caribbean Island of Saint Lucia

“…They used a different solvent and different ratio between plant material and solvent. The strong effect of moringa leaves' drying methods on total phenolics (and other compounds, as well) was shown by [51]. They found from 47 to 69 mg GAE/g DM.…”

“…Much higher yield (18.8%) was obtained by [8], who extracted crushed leaves with a methanol-water mixture (80:20) for three days. The effect of various methods of moringa leaves' drying followed by extraction with water (the ratio 1 g of leaves to 100 ml distilled water) for 24 h, yielded approximately 44% for each sample [51]. Another study reported the amount of phenols in methanol extracts of moringa leaves from India as 118 mg/g, which is almost 12% [52].…”

Fluted pumpkin ( Telfairia occidentalis ) seed modulates some markers of erectile function in isolated rat’s corpus cavernosum: Influence of polyphenol and amino acid constituents

“…This could result from the ability of the abundant phytoconstituents in this seed extract to chelate Fe 2+ and scavenge NO radicals produced from the decomposition of SNP (Gaurav, Apminder, & Giridhar, ). Earlier reports have shown that this might be the mechanical process by which phenolics are able to protect the tissues against Fe 2+ and SNP‐induced peroxidation of lipids (Ademiluyi, Aladeselu, Oboh, & Boligon, ; Oboh et al, ). Previous studies have reported that fluted pumpkin seed possesses some essential constituents such as vitamin A, tannins, oleic acid, linoleic acid, and alkaloids which are involved in the suppression of lipid peroxidation in testes with concomitant improved erectile functions (Akintayo, ; Glenville, ; Nkang et al, ).…”